Ski for retractable undercarriages



9 24, 1940- B. w. SZNYCER SKI FOR RETRACTABLE UNDERCARRI AGES Filed Aug. 15. 1938 Fiai BERNARD W SZA/YCER INVENT OR.

ATTORNEY.

Patented Sept. 24, 1940 UNITED STATES PATENT OFFICE 4 Claims.

My invention relates to skis for retractable undercarriages of airplanes and has particular reference to skis adapted to be mounted on the undercarriage in place of landing wheels.

In view of the fact that skis are mounted on the airplanes only in winter or for special trips into polar regions, the usual practice is to provide skis with attachments for fitting them on the wheel shafts of the undercarriages in place of landing wheels. With retractable undercarriages, however, a difficulty arises from the fact that the skis will have tendency to turn into a vertical position when the undercarriage is rotated for bringing it into the fuselage. My invention has for its object, therefore, to provide a ski mounting with a special arrangement for maintaining the ski in a parallel alignment with the fuselage for all positions of the undercarriage. For this purpose I provide a removable attachment between the shaft and fixed points in the fuselage, the attachment representing a hinged parallelogram adapted to maintain its lower cross member in a constant alignment in relation to the fuselage. By connecting the ski to the cross member, the constant alignment is obtained also for the ski.

Another object of my invention is to provide a resilient yieldable connection between the ski and the supporting attachment. For this purpose I mount a shock absorber between the cross member of the parallelogram and the ski in order to resiliently maintain the fixed position of the ski while permitting certain deflections when the ski hits the ground at one end, in order to bring the whole surface of the ski to bear on the ground.

My invention is more fully described in the accompanying specification and drawing in which:

Fig. 1 is an elevational view of my ski with the undercarriage attachment for an airplane.

Fig. 2 is an end view of the same.

My ski comprises a runner I with a bracket 2 supporting a tubular bearing 3 adapted to be rotatively fitted on a shaft 4 of a retractable undercarriage frame 5. The upper end of the frame is mounted for rotation on a shaft 6, supported in brackets I6. A worm gear I is mounted on the frame concentrically with the upper shaft and is in mesh with a worm 8 on a shaft 9 of an electric motor ID. The motor is used for rotating the frame between its operative position as shown in full lines in Fig. 1 and its retracted position as shown in dotted lines in the same figure. The bottom of the fuselage or a gondola II is trimmed for a snug fit of the runner as shown in dotted lines in Fig. 1, a recess I! being provided for the raised front end of the ski runner.

In order to bring the runner into the proper retracted position, it is necessary to maintain the 5 runner in a fixed horizontal, or parallel with the fuselage, position during rotation of the frame. For this purpose an arrangement is provided consisting of a rocker arm l2 rotatively mounted on the lower shaft 4. The ends of the arm have piv- 10 ots l3 connected with the lower ends of rods l4 whose upper ends are pivotally supported at IS on brackets l6 mounted on the inner wall of i! of a fuselage or gondola H. The rods it are mounted in parallel alignment with the frame 15 5 and form a hinged parallelogram adapted to retain the rocker arm l2 in a fixed alignment in relation to the fuselage as shown in dotted lines in Fig. 1 when the ski is fully retracted and pressed against the lower portion of the fuselage. 20

In order to provide a yieldable and resilient connection between the ski and the rocker arm,

a stabilizer is mounted on the shaft 4 consisting of two arms I!!! and 20 connected together by a resilient shock absorber 25, the arms having elon- 25 gated slots (not shown) engaged by a pin 22 extending from the ski. The slots in the arms admit of a certain freedom of movement for the arms against the resistance of the shock absorber, the latter tending to maintain the ski in a 30 horizontal position or, generally speaking, in a fixed alignment with the fuselage. The construction of the stabilizer is more fully described in my copending patent application, Serial Number 224,898, now matured into Patent 2,142,807 of 85 January 3, 1938, although other types of stabilizers may be also used.

The brackets l6 remain permanently attached to the fuselage, but the rods It with the rocker arm i2, stabilizer and the ski are removed when 40 it is desired to mount a landing wheel.

It is understood, of course, that two undercarriages and two skis are used for an airplane, one at each side.

I claim as my invention: 45

l. A ski for a retractable undercarriage of an airplane comprising a runner, a bracket on the runner, a tubular bearing supported on the bracket transversely to the runner, adapted to be rotatively fitted on the lower shaft of a frame 50 of the undercarriage in place of a landing wheel,

a rocker arm rotatively supported at its middle portion on the shaft, a resilient shock absorber yieldably connecting the rocker arm with the runner bracket and tending to yieldably maintain constant alignment between the rocker arm sitions of the undercarriage.

2. A ski for a retractable undercarriage of an airplane comprising a runner, a bracket on the runner, a tubular bearing supported on the bracket transversely to the runner adapted to be rotatively fitted on the lower shaft of a frame of the undercarriage in place of a landing wheel, a rocker arm rotatively supported at its middle portion on the shaft, pivots at the ends of the rocker arm in line with the center of the shaft, rods extending from the pivots to the upper end of the undercarriage, pivots supporting the upper ends of the rods on the fuselage of the airplane,

the rods and the rocker arm with the upper pivoted supports forming a hinged parallelogram adapted to maintain the rocker arm in a fixed alignment with the axis of the fuselage, and a shock absorber resiliently connecting the rocker arm with the ski and adapted to yieldably maintain the ski in a fixed alignment with the rocker arm.

3. A retractable undercarriage for an airplane ski comprising a frame rotatively supported at its upper end in the fuselage of the airplane, a shaft at the lower end of the frame, adapted to rotatively support a ski, a rocker arm rotatively supported at its middle portion on the shaft, a resilient yieldable connection between the rocker arm and the ski, and pivoted connections between the ends of the rocker arm and the fuselage forming a hinged parallelogram adapted to maintain the rocker arm in a fixed alignment in relation to the fuselage for all positions of the undercarriage frame.

4. A retractable undercarriage for an airplane ski comprising a frame rotatively supported at its upper end in the fuselage of the airplane, a shaft at the lower end of the frame, adapted to rotatively support a ski, a rocker arm rotatively supported at its middle portion on the shaft, a resilient yieldable connection between the rocker arm and the ski, pivots at the ends of the arm in line with the center of the shaft, and rods BERNARD W. SZNYCER. 

